1. Field of the Invention
Embodiments of the present invention generally relate to a method of cleaning a processing chamber using a remote plasma source and in situ radio frequency (RF) power.
2. Description of the Related Art
In the fabrication of integrated circuits and semiconductor devices, materials such as oxides are typically deposited on a substrate in a processing chamber, such as a deposition chamber, e.g., a chemical vapor deposition (CVD) chamber. The deposition processes typically result in deposition of some of the material on the walls and components of the deposition chamber. The material deposited on the chamber walls and components can affect the deposition rate from substrate to substrate and the uniformity of the deposition on the substrate.
Similarly, when materials such as oxides are etched from a substrate in a processing chamber, such as an etching chamber, some of the materials that are removed from the substrate typically are deposited on the walls and components of the etching chamber. The material deposited on the chamber walls and components can affect the uniformity and consistency of etching processes performed in the chamber.
Several methods of cleaning processing chambers have been developed. For example, a remote plasma source can be used to provide a source of reactive species, such as fluorine radicals, that react with deposited material in a processing chamber, forming volatile compounds that can be removed from the processing chamber. However, cleaning a processing chamber using known remote plasma sources is a time consuming process. Remote plasma sources typically provide reactive species, such as free radicals, at a flow rate and an intensity that do not result in a level of free radical or ion bombardment that can damage the deposition chamber. However, more time is required to clean a chamber when a low intensity cleaning process such as a remote plasma clean process is used. A lengthy chamber cleaning period decreases the number of substrates that can be processed in a given time, since the chamber typically cannot be used for processing during the cleaning period.
Providing in situ radio frequency (RF) power in a processing chamber to generate a plasma of cleaning gases is another method that can be used to clean a processing chamber. Reactive species generated in the plasma bombard and react with deposited material in the processing chamber, forming volatile compounds that can be removed from the deposition chamber. The reactive species can also bombard the chamber and remove deposited material from the chamber surfaces. However, the reactive species often damage the chamber due to the energy imparted to the species in the chamber. Furthermore, the reactive species can react with the material forming the chamber lining and create undesirable contaminants that may land on and harm a substrate undergoing processing in the chamber. For example, if NF3 is introduced into a chamber, the fluorine ions generated in the plasma can combine with aluminum used as a lining material in the deposition chamber and form particles of aluminum fluoride.
The removal of contaminating particles from a processing chamber is becoming increasingly important because the device sizes are becoming smaller and aspect ratios are becoming more aggressive. With smaller feature sizes and more aggressive aspect ratios, the size and number of contaminating particles must be minimized in order to maintain the performance of the device.
Therefore, there remains a need for a method of cleaning processing chambers efficiently, while minimizing contaminant generation.